Year 10 GCSE Maths (Age 15) — Rounding to Decimal Places Worksheet

Instructions

To round a number to a specific number of decimal places (d.p.), follow these steps:

1. Identify the 'rounding digit' in the place you are rounding to.
2. Look at the digit immediately to its right. This is the 'decider digit'.
3. If the decider digit is 5 or more, you 'round up' (add one to the rounding digit).
4. If the decider digit is 4 or less, you 'leave it' (the rounding digit stays the same).
5. Write your new number, stopping after the rounding digit. Don't forget any 'carried over' numbers!

Example: Round 8.537 to 2 decimal places (2 d.p.).

• The second decimal place is the '3'. This is the rounding digit.
• The digit to its right is '7'. This is the decider.
• Since 7 is 5 or more, we round the '3' up to '4'.
• Answer: 8.54

Example 2: Round 29.96 to 1 decimal place (1 d.p.).

• The first decimal place is the '9'. This is the rounding digit.
• The digit to its right is '6'. This is the decider.
• Since 6 is 5 or more, we round the '9' up. This becomes '10', so we write 0 and carry the 1 over.
• Answer: 30.0 (The .0 is important to show it has been rounded to 1 d.p.)

Section A: Rounding to 1 Decimal Place

Round the following numbers to one decimal place (1 d.p.).

1. 12.78   _______________
2. 5.629   _______________
3. 0.951   _______________
4. 45.97   _______________
5. 199.949   _______________
6. 8.035   _______________

Section B: Rounding to 2 Decimal Places

Round the following numbers to two decimal places (2 d.p.).

1. 7.8251   _______________
2. 14.038   _______________
3. 0.599   _______________
4. 63.9962   _______________
5. 3.1049   _______________
6. 0.005   _______________

Section C: Mixed Rounding

Complete the table below. Round each number to the required number of decimal places.

Section D: Application Problems

Read the questions carefully and give your answers to the required degree of accuracy.

1. A plank of wood measures 5.852 metres long. A builder needs to record its length to one decimal place for his project plan. What length should he write down?
   
   Answer: _______________ metres
   
   
2. Four friends go out for a meal. The total bill comes to £97.48. They decide to split the bill equally. How much does each person have to pay? (Note: Money is always given to two decimal places).
   
   Answer: £ _______________
   
   
3. The value of Pi (π) is an irrational number that goes on forever. A common approximation is 3.14159265359. A NASA engineer needs to use the value of Pi rounded to three decimal places for a calculation. What value will she use?
   
   Answer: _______________